【摘要】 2013年4月20日发生在四川芦山的7.0级地震位于龙门山断裂带南段,文中通过分析震区青衣江上游流域地貌的构造响应与典型的震灾特征,研究此次地震的发震构造机理。对穿越龙门山断裂带南段的青衣江上游水系地貌特征及流域盆地面积-高程积分的分析结果表明:该地区流域地貌发育对龙门山断裂带的新活动具有明显的反馈作用。在芦山地震中,遭受严重破坏的建筑物呈条带状分布,并产生大量次生地表张性地裂缝、串珠状砂土液化等地表破坏现象,其展布方向均与震区中的主断裂和背斜隆起相平行。余震分布表明,芦山地震与本区的双石—大川断裂、新开店断裂和大邑断裂的新活动有关。龙门山断裂带为典型的逆冲推覆构造,具有前展式发育特征,芦山地震的发震构造就具有该特征。综合龙门山南段的地貌响应过程、芦山地震的地表破坏及余震分布特征,认为芦山7.0级地震应为龙门山断裂带持续向SE逆冲扩展、地壳挤压缩短的产物。更多还原

【Abstract】 On April 20,2013,in Sichuan Province,the Lushan MS7.0earthquake occurred on the southern segment of the Longmenshan fault belt.Through the analysis of the upstream geomorphology and the typical earthquake destruction characteristics,we probed into the seismogenic tectonic mechanism of the Lushan MS7.0earthquake in this paper.The analysis of the geomorphic features of the upstream drainages and hypsometric interval(HI value)of the drainage basins showed that the landscape development has obvious feedback effect on the neotectonic activities of the Longmenshan fault belt.The buildings,destroyed seriously in the earthquake,distributed as bands.The earthquake produced a large number of secondary surface tension cracks and a series of beaded liquefaction.The distribution of the surface destruction phenomenon was in parallel with the main faults and anticline.The aftershock distribution showed that the Lushan earthquake was closely related with the new activities of the Shuangshi-Dachuan fault,Xinkaidian fault and Dayi fault.The Longmenshan fault zone is a typical thrust-nappe structure.And the seismogenic structure of the Lushan earthquake has the same characteristics.Upstreams of the Qingyijiang river cross the southern segment of the Longmenshan fault belt.Combining the geomorphological response process of the southern segment of the Longmenshan,the characteristics of the surface damages of the Lushan earthquake and the aftershock distribution,the Lushan earthquake was ascribed to the result of the ceaselessly propagating of the Longmenshan thrust fault belt in SE direction and the compression and shortening of the crust.更多还原